The present invention relates to a sheet separator for separating adjacent sheets of recording media being fed from a stack of sheets, so that only one sheet is fed to a process station, such as a print engine of a printer or copier.
One mechanism for feeding cut sheet recording media from a stack of sheets frictionally engages the topmost sheet to slide the topmost sheet toward a process station, such as a print engine of a printer of copier. On occasion, the next adjacent sheet in the stack may be propelled along with the topmost sheet, causing a “multi-feed” situation. One contributor to such multi-feed situations is that when the paper manufacturer cuts the paper to form the stack of cut sheets, the edges of adjacent sheets may partially fuse together, a situation sometimes referred to as edge welding.
In a media tray, a sheet feed mechanism capable of feeding heavy recording media has an increased probability of improperly feeding multiple sheets of a lighter weight recording media. Some apparatus incorporate sensors to detect multi-feed situations and take corrective action.
The present invention encompasses a simplified mechanism to separate multiple sheets of recording media fed from a media tray, which mechanism does not depend on sensors, and still permits a wide range of media weights to be used.
In accordance with an aspect of the present invention, an apparatus for separating a sheet of recording media from a stack of sheets includes a support for supporting a stack of sheets of recording media, and a plurality of inclined separator strips. The separator strips are substantially parallel to one another, and the surface of each inclined separator strip is oriented at an obtuse angle relative to the sheets of the stack of sheets. At least one of the inclined separator strips is a retard separator strip that includes a first separator surface and a second separator surface. The first separator surface is closer to the stack of sheets then is the second separator surface, and the second separator surface has a higher coefficient of friction than does the first separator surface.
In accordance with another aspect of the present invention, an apparatus for separating a sheet of recording media from a stack of sheets includes a support for supporting a stack of sheets of recording media and a plurality of inclined separator strips in which the inclined separator strips are substantially parallel to one another, and the surface of each inclined separator strip is oriented at an obtuse angle relative to the sheets of the stack of sheets. At least one of the inclined separator strips is a retard separator strip that includes a first separator surface and a second separator surface, and in which the first separator surface is closer to the stack of sheets than is the second separator surface. The plane of at least a portion of the first separator surface is above the plane of the second separator surface.
In accordance with yet another aspect of the present invention, a sheet separator element for use in a sheet feed path of a printing device includes a first separator surface and a second separator surface, in which the second separator surface has a higher coefficient friction than does the first separator surface, and wherein the plane of at least a portion of the first separator surface is above the plane of the second separator surface.
In accordance with yet another aspect of the present invention, a sheet separator element for use in a sheet feed path of a printing device includes a first separator surface comprising a distal segment and a proximal segment, and a second separator surface. A proximal segment of the first separator surface forms an obtuse angle with the distal segment of the first separator surface, and the proximal segment of the first separator surface is between the second separator surface and the distal segment of the first separator surface. The plane of the proximal segment of the first separator surface at an edge nearest the second separator surface is above the plane of the second separator surface. The plane of the proximal segment of the first separator surface and the plane of the second separator surface are oriented at an oblique angle with respect to one another. The distal and proximal segments of the separator surface have a first coefficient of friction, and the second separator surface has a second coefficient friction, higher than the first coefficient friction.
In accordance with yet another aspect of the present invention, a method of separating a sheet of recording media from a stack of sheets includes urging two or more topmost sheets of a stack of sheets toward a plurality of inclined separator strips, wherein at least of one of the inclined separator strips is a retard separator strip. The method further includes causing the topmost sheets to move upward along a first separator surface of the retard separator strip until a leading edge of the topmost sheets moves past an edge of the first separator surface. After the topmost sheet has moved along the first separator surface of the retard separator strip, causing a leading edge of one of the topmost sheets to engage in a second separator surface of the retard separator strip, wherein the second separator surface has a higher coefficient of friction than does the first separator surface. The method further includes continuing to urge the topmost sheet along the retard separator strip so that the first topmost sheet moves while the second topmost sheet is restrained by the second separator surface of the retard separator strip.